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Topography-guided photorefractive keratectomy for correction of irregular astigmatism following penetrating keratoplasty

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Session Details

Session Title: Refractive Corneal Surgery

Session Date/Time: Wednesday 17/09/2014 | 08:00-09:30

Paper Time: 08:53

Venue: Boulevard A

First Author: : J.Tan SINGAPORE

Co Author(s): :    G. Moloney   D. Lin   S. Holland        

Abstract Details


To report results of custom Topographic Neutralization Technique (TNT) in topography-guided Photorefractive Keratectomy (TGPRK) for correction of irregular astigmatism following penetrating keratoplasty (PK).


Pacific Laser Eye Centre, Vancouver, BC, Canada


Retrospective, non-randomized, consecutive series of eyes with irregular astigmatism following PK were treated with TGPRK with ALLEGRETTO WAVE Eye-Q Excimer laser, utilizing Topography-guided Customized Ablation Treatment and TNT. Preoperatively and postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction and topographic cylinder were analyzed. Eyes with at least 12 months of follow-up were included.


65 eyes underwent TGPRK, of which 39 eyes met the inclusion and exclusion criteria for analysis. The mean follow-up was 18.2 months. 14 eyes had UDVA of 20/40 or better, while none had that vision preoperatively. Mean spherical equivalent was -1.96±2.14 dioptres (D) preoperatively, and improved by 0.91D to -1.05±1.79D postoperatively. Manifest cylinder improved from -4.53D (range -0.75 to -8D) to -2.16D (range -0.5 to -7D). 9 eyes were within 0.5D of the attempted correction, while 17 eyes were within 1.0D of the attempted correction. 2 eyes lost two or more lines of CDVA, while 12 eyes gained two or more lines of CDVA.


Early results of TGPRK with TNT show potential to improve vision in eyes with post keratoplasty astigmatism with good efficacy and safety.

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